Testing Dialog having it in a shared module

confirm-dialog.component.html

<h1 md-dialog-title>Would you like to order pizza?</h1>
<md-dialog-actions>
  <button (click)="dialogRef.close('yes')">Yes</button>
  <button md-dialog-close>No</button>
</md-dialog-actions>

confirm-dialog.component.js

import { Component, OnInit } from '@angular/core';
import { MdDialogRef } from '@angular/material';

@Component({
  selector: 'app-confirm-dialog',
  templateUrl: './confirm-dialog.component.html',
  styleUrls: ['./confirm-dialog.component.scss']
})
export class ConfirmDialogComponent implements OnInit {

  constructor(public dialogRef: MdDialogRef<ConfirmDialogComponent>) { }

  ngOnInit() {
  }

}

confirm-dialog.component.spec.js

/* tslint:disable:no-unused-variable */
import { async, ComponentFixture, TestBed, inject } from '@angular/core/testing';
import { By, BrowserModule } from '@angular/platform-browser';
import { DebugElement, NgModule } from '@angular/core';
import { MdDialogModule, MdDialog, OverlayContainer, MaterialModule } from '@angular/material';
import { BrowserDynamicTestingModule, platformBrowserDynamicTesting } from '@angular/platform-browser-dynamic/testing';




import { ConfirmDialogComponent } from './confirm-dialog.component';
import { SharedModule } from '../shared.module';

@NgModule({
  declarations: [ConfirmDialogComponent],
  exports: [ConfirmDialogComponent],
  entryComponents: [ConfirmDialogComponent],
  imports: [MdDialogModule],
})
class DialogTestModule { }



describe('ConfirmDialogComponent', () => {
  let component: ConfirmDialogComponent;
  let dialog: MdDialog;
  let overlayContainerElement: HTMLElement;




  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [DialogTestModule, MdDialogModule.forRoot()],
      providers: [
        {
          provide: OverlayContainer, useFactory: () => {
            overlayContainerElement = document.createElement('div');
            return { getContainerElement: () => overlayContainerElement };
          }
        }
      ],

    })
      .compileComponents();
  }));

  beforeEach(() => {
    dialog = TestBed.get(MdDialog);
    let dialogRef = dialog.open(ConfirmDialogComponent);

    component = dialogRef.componentInstance;
  });

  it('should create', () => {
    expect(component).toBeTruthy();
  });


});

main.module.js

import { AuthService } from './shared/auth.service';
import { AlertService } from './shared/alert.service';
import { ToolbarService } from './shared/toolbar.service';

// Material
import { MaterialModule } from '@angular/material';

// Layout
import { FlexLayoutModule } from '@angular/flex-layout';

// Shared
import { SharedModule } from './shared/shared.module';

// Auth
import { AuthModule } from './auth/auth.module';

// Admin
import { AdminModule } from './admin/admin.module';

// Covalent
import { CovalentDataTableModule } from '@covalent/core';

import 'hammerjs';



@NgModule({
  declarations: [
    AppComponent,
  ],
  imports: [
    BrowserModule,
    FormsModule,
    HttpModule,
    MaterialModule.forRoot(),
    FlexLayoutModule.forRoot(),
    SharedModule,
    routing,
    HomeModule,
    LawModule,
    AuthModule,
    AdminModule,
    CovalentDataTableModule.forRoot(),
  ],
  providers: [MenuService, AlertService, AuthService, ToolbarService],
  bootstrap: [AppComponent]
})
export class AppModule { }

shared.module.js

import { NgModule, } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';


import { TitleCasePipe, TruncatePipe } from './';

// Material
import { MaterialModule } from '@angular/material';

// Layout
import { FlexLayoutModule } from '@angular/flex-layout';
import { ConfirmDialogComponent } from './confirm-dialog/confirm-dialog.component';
// Covalent
import { CovalentDataTableModule } from '@covalent/core';


@NgModule({
    imports: [CommonModule, MaterialModule, FormsModule, FlexLayoutModule, CovalentDataTableModule, ReactiveFormsModule],
    exports: [TitleCasePipe, TruncatePipe, MaterialModule, FormsModule, FlexLayoutModule, CovalentDataTableModule, ReactiveFormsModule],
    declarations: [TitleCasePipe, TruncatePipe, ConfirmDialogComponent],
    entryComponents: [ConfirmDialogComponent],
    providers: [],
})
export class SharedModule { }

MaterialModule.forRoot() complained for me ("forRoot doesn't exist... something, something"). It worked when skipped any mention of it in main.module.